The previously unexplained characteristics of the ice giant Uranus have long interested astronomers. It is believed that all planets in the solar system revolve around the sun in the same direction and in the same plane. This, according to scientists, is a sign that our solar system was formed from a rotating disk of gas and dust. Most planets also rotate in the same direction, with their poles oriented perpendicular to the plane in which the planets rotate. However, it is Uranus that has a significant difference – its axis has an inclination of about 98 degrees.
Uranus, like Saturn, has a ring system and has 27 satellites in its orbit. Thus, the satellites are also tilted relative to the plane of the ecliptic. A research group led by Professor Shigeru Ida from the Institute of Earth and Life Sciences (ELSI) at the Tokyo Institute of Technology undertook to explain the unusual properties of the planet. Their research suggests that early in the solar system's history, Uranus was struck by a small icy planet about three times the mass of Earth, which toppled the young planet and left behind its unique lunar-ring system.
This allowed a group of scientists to create a completely new computer model of the formation of satellites. So most of the planets in the solar system have satellites of different sizes, orbits, compositions and other properties, which, scientists believe, can help explain the nature of their formation. In addition, today the prevailing theory is that the moon was formed as a result of the fact that a rocky body about the size of Mars hit our planet 4.5 billion years ago. The theory explains a lot about the Earth, the composition of the Moon, and how the Moon revolves around the Earth.
It is believed that at the very beginning of the existence of our Universe, such collisions were not a rare event. Most likely, Uranus was influenced by external threats, somewhat different from those to which the Earth was subjected. Scientists are sure that this happened precisely because the planet was much farther from the sun.
The Earth was formed closer to the Sun, that is, its environment was much warmer. The main composition of our planet is made up of the so-called 'non-volatile' elements, that is, they do not form gases at normal pressures and temperatures on the Earth's surface – they are made of stone. That being said, the outer planets are mainly composed of volatile elements such as water and ammonia. These gases or liquids are subject to extreme temperatures and pressures. In conditions of considerable distance from the Earth, at great distances from the Sun, they turn into solid ice.
Gigantic impacts on distant icy planets will be completely different from impacts associated with rocky planets, such as the impact that scientists believe formed the Earth's satellite, according to a study by Professor Ida and his colleagues. Given that water ice forms at low temperatures, during the collision of Uranus and its ice impactor, the released fragments evaporate.
In the case of Uranus, scientists believe that a large icy body could tilt the planet and give it additional rotation (currently, a day on Uranus is about 17 hours, that is, it passes even faster than on Earth). Small fragments that arose as a result of the collision later became satellites of the gas giant.
